Snap action valve mechanisms



Jan. 22, 1935. R. E. NEWELL SNAP ACTION VALVE MECHANISMS Filed July 26,1930 Patented 1935 UNITED sr rE s PATENT OFFICE.

The present invention relates broadly to the art of fluid distribution,and more particularly to an improved valve of the so-called snap actiontype, especially useful for the control of gas. or

fluid burners.

Developments in the art, and more particularly with respect to gas andfluid burners, have been such as to make it desirable to utilize snapaction valves for controlling the fuel supply thereto. The present.invention has for one of its objects the provision of an improved valvestructure possessing desirable characteristics with respect to a snapopening or closing, and suitable for use in systems wherein either atemperature or pressure variation is available for controlling purposes.

In the accompanying drawing I have shown for purposes of illustrationonly, certain preferred embodiments of the present invention.

In the drawing, Figure 1 is a longitudinal sectional view through oneform of thermostatic valve constructed in accordance with the presentinvention;

Figure 2 is a top plan view, partly broken away,

of a valve of the type illustrated in Figure 1;

Figure 3 is a detail sectional view, on an enlarged scale, of the valvedisk;

Figure 4 is a detail sectional view, on an enlarged scale, of theadjustable stop screw; and

Figure 5 is a view partly in elevation, partly in section and partlybroken away, illustrating an-' other embodiment of the invention.

It has heretofore been proposed to provide valves of the snap actiontype in which th snap action has been obtained by means of a disk ofspring metal adapted to be flexed from one position of concavity intoanother position, the movement being relied upon to obtain the desiredoperation of the part being controlled. Such structures, whileresponsive to the conditions which it is desired to control, are open tocertain objections, depending upon their particular constructionalcharacteristics. In some cases the operating disk is perforated at itscenter portion whereby the disk is correspondingly weakened and itssensitiveness is impaired. In most cases the disk has been held againstmovement at one portion thereof, whereby a uniform flexing action hasnot been obtainable. Also in most cases with whichI am familiar it hasbeen considered desirable to so construct the disk that it will have adifierent amount of movement in one direction than in the other tothereby give it the required sensitiveness of operation, and to utilizea lost motion connection between the disk and the second for the reasonthat the lost motion connection has required installation of the valvein a predetermined manner such that the pressure of the gas or otherfluid beingcontrolled will not be effective for opening the valve to theextent permitted by the lost motion present in the valve structure.

In accordance with the present invention there is provided aconstruction in which the disadvantages and objections before referredto are obviated, and correspondingly improved operating results andcharacteristics obtained.

As illustrated in Figure 1 of the drawing, there is provided a valvecasing 2 having a seat 3 therein adapted to be controlled by a valvedisk 4. As is customary in structures of this type, the seat isintermediate the inlet and outlet ports or connections 5 so as tocontrol the flow of fluid through the casing.

Secured within the casing is a tube 6 having a relatively highcoeflicient of expansion, the tube containing a rod 7 having either anegligible or relatively low coefficient of expansion. By reason of thisconstruction, it will be apparent that if the tube 6 is subjected to thetemperature of the medium which it is desired to control, the

, tube will tend to contract as the medium cools in temperature, andthereby move the rod 7 upwardly as indicated in Figure 1 oi the drawing.This upward movement will in turn be transmitted to a lever 8 having anadjustable fulcrum in the form of a temperature adjusting screw 9. Themovement of the lever is transmitted to a flexible disk 10 illustratedin Figures 1 and 3 of the drawing as convexed upwardly with the valvedisk in seated position.

The flexible disk is carried by the valve disk 4 in such manner as notto interfere with the free flexing of the disk. Desirable results may beobtained by providing the disk with a flange or rib 11 adapted to beturned inwardly over the edge of the flexible disk and thus hold it inposition, the upper surface 12 of the valve disk being cut away belowthe flexible disk so as to permit movement to the extent permitted bythe engagement bea tween a shoulder 16 on the push pin and the shoulderformed by the inturned edge 17 on the stop screw. The construction ofthe parts is conveniently such that the free end of the push pin 15extends beyond the end of the adjustable stop screw a short distanceequal to slightly more than half of the total flexing distance of thedisk 10. The outside diameter of the upper end of the stop screw 13 issuch as to slide easily within a central opening 18 in the valve disk.

Extending through a cap 19 carried by the valve casing is an adjustablescrew 20 carrying a disk 21 at its lower end. This disk, and the screwperature conditions, it will be apparent that the downward pressure ofthe lever 8 against the convex upper side of the disk 10 will betransmitted to the valve disk 4 and will be in opposition to the spring14 and the push pin 15. This tends to press the valve disk 4 moretightly into engagement with its seat, this condition continuing andbecoming greater and greater until the critical point is reached. Atthis point the disk 10 will spring to an opposite curvature. This willcause the peripheral edge of the disk to move upwardly, thereby liftingthe valve disk 4 away from its seat to the extent permitted by theengagement of pins 23a carried by the valve disk, with the disk 21 onthe adjustable screw 20.

The flexible disk having been sprung to an opposite curvature, andhaving thereby'opened the valve, retains the valve in such openedposition until such time as the temperature of the medium beingcontrolled increases to an extent sufflcient to expand the tube 6,thereby releasing the lever 8 from the holding influence of the rod 7andpermitting the spring 14 through the push pin 15 to push the flexibledisk 10 in the opposite direction to an extent sufiicient to cause it toresume its original position. In resuming this.

original position and in snapping to the opposite curvature, the valvedisk 4 will again be brought into engagement with its seat. j

It is to be pointed out that the valve structure just described ischaracterized by the fact that during such period of time as the valveis preparing to open, it is gradually pushed tighter and tighter towardits seat, thereby precluding any possibility of leakage until a criticaltemperature has been reached. It is also to be noted that theconstruction of the flexible disk is such that pressures exerted ineither direction are evenly spread over its whole area and not -soconcentrated in small sections thereof as to tend to over-strain themetal.

The disk is also characterized by a total movement which is the same inopposite directions and which is the same at the center of the disk asat the outside, thereby distinguishing from structures as heretoforeused in which either the outer edge is relatively stationary while thecenter is snapped, or in which'the center is relatively sta-:

tionary while the outer edge is snapped.v -A construction of thecharacter disclosed herein .obtains the advantage of a more perm'anentand de pendable snap action for the reason that the equalized movementof the flexible disk is such that the tension or tendency to snap isequal on both sides. With other types of the character referred to inwhich most of the'tension is placed on one side of the disk with only aslight tension on the other side, there is not a uniform action in bothdirections.

The general construction of the valve having beenreferred to, the stepsnecessary to effect a setting of the parts for actual operation will nowbe described.

Assume the flexible disk 10 to be so flexed that its center is up asillustrated in Figures 1 and 3, and the concave side downwardly, withthe valve disk 4 in positiononthe seat 3.- The adjustable stop screw121' willbe threaded inwardly until the push pin 15 almost contactsvalve disk 10. The

indicator 24 carried by the fulcrum temperature adjusting screw 9 willthen be set to cold position, the tube 6 being screwed out of positionif necessary so that the lever 8 will drop into place. By then pressingfirmly on the long end of the lever 8 the push pin 15 will be-caused torecede into the adjustable stop 13 until the flexible disk 10 rests onthe upper end of the stop screw 13 itself. The stop screw will then bethreaded outwardly by means of a screw driver until the valve disk 4 issnapped to open position by the flexing action of the flexible disk 10,the reversal of curvature of the flexible disk causing its outside edgeto move upward with a corresponding movement of the valve disk.

The thermostat is now ready for calibration, which is accomplished inthe following manner. The tube 6 is submerged in water or the like at atemperature, for example, of 123. The indicator 24 is set at ,-7 higherthan the water temperature. The outer edges of the valve disk are thenpressed downwardly so thatthe valve disk is seated. The tube 6 is thenslowly screwed inwardly until its action on the lever 8 causes the valvedisk to snap to open position. The thermostat is now calibrated foropening at any temperature 7 lower than the indicator setting.

Assuming that it is desired to have the valve preset at a temperature 7higher than the indi-- cater setting, so that the indicator wherever itis placed will always be at a point half way between the actual openingand closing temperatures at which the valve will operate, the followingprocedure is resorted to. The cap 19 is screwed into position, theadjustable back stop screw 20 having been screwed outwardly so as not topermit the disk 21 to engage the pins 23a when the valve disk 4. is inopen position. The tube 6 is then inserted in water at a temperature of137, and the'stop 20 is slowly screwed inwardly until the valve disk isheard to snap to closed position. The thermostat is then ready forservice. I

In Figure 5 there is illustrated a construction in which partscorresponding to parts already described are designated by the samereference characters having, however, a prime afiixed thereto.

In this embodiment of the invention, the tube 6 and rod 7 of Figure 1are replaced by a bellows 25 within a suitable housing 26 which isthreaded onto a boss 27 projecting from the valve casing 2'. Theperiphery of the lower flange 28 of the housing 26 may be calibrated tocooperate with an indiactor or pointer 24' projecting outwardly from thevalve casing. I

For cooperation with the seat 3' is a valve disk 4 carrying a flexibledisk 10'. The lever B of Fig ure 1 is replaced by a push pin 8 adaptedto be actuated by the bellows 25, the action, however, being the reverseof that obtained with the construction of Figure 1 in that when thebellows cools due to a decrease in the temperature of the medium towhich it is subjected, it contracts and thereby relieves pressure fromthe pin 8'.

This release of pressure from the pin 8 permits the push pin 15', underthe influence of the spring 14 to move upwardly, thereby exertingpressure against the under side of the center of and consequentlytemperature ranges. By setting the back stop closer to the valve disk tolimit the movement thereof, a smaller capacity will be obtained and avery much smaller temperature range, while by moving it in the oppo-'site direction, the opposite results will be obtained. The outer end ofthe adjustable back stop may be housed within a suitable cap 29.

With reference to the structure just described, it will be assumed thatinstead of calibrating it to exact maximum and minimum temperatures, aswas disclosed inconnection with the valve of Figures 1 to 4, leavingthecapacity to be what it may, it is desired to set the valve for an exactmaximum capacity, leaving the total temperature range to come as it may.Either method may be used on both types of thermostata Under thecondition just assumed, the parts will be assembled approximately asillustrated in Figure 5, taking care that the flexible disk 10' issnapped to open position, i. e., with the concave side facing the pushpin 15'. The adjustable stop screw 13' 'will be threaded inwardly untilthe back of the valve disk 4 is about one-sixteenth of an inch from theback stop 12'. The operator will then press down firmly on the pin 8with one hand, while with the other hand the adjustable stop screw 13'will be backed out slowly until a snap is heard, which means that theback of the valve disk 4' has engaged the adjustable back stop 12pressing against the outer edge of the flexible disk 10' and thatcontinued pressure on the rod or pin 8' has caused the outer edge of'theflexible disk 10' to spring upwardly and throw the valve disk intoclosed position.

The downward pressure on the rod 8' is then released, and the back stop12' gradually screwed inwardly until the valve disk touches its seat.This movement is continued until the valve disk snaps to open position.The thermostat may then be submerged in water at a temperature of 75.for example, and the housing 26 turned to bring pressure on the rod 8'until such time as the valve disk snaps to closed position. Theindicator of the thermostat may then be set, for example, at 73. Thethermostat is then calibrated to snap to closed position at 2 above theindicator setting. With the indicator in the same position, thethermostat may be placed in water at 71.

. If the bellows is designed to operate the valve with a maximum snapcapacity with a 4 temperature range, the valve should snap open againwith water at 71. If the snap does not occur, the indicator may be movedcarefully until the snap is heard. The pointer of the indicator or theindicator dial may then be loosened and readjusted to one-half of thetotal variation. In

' this way the indicator pointer is maintained half way between theactual valve opening and closing temperatures.

It will be understood that any further adjustment inwardly of the backstop screw 12' will decrease the capacity of the valve as well as therange in temperature in a manner generally similar to that obtained withthe structure of Figure 1. Any limiting of the snap disk movement byadjustment of the back stop screw. also reduces the movement required atthe center to reverse its snap action, as the movement at thev centerand at the outside periphery of the disk is always equalized, asreferred to.

Even though the construction of Figure 5 operates in certain respects onthe opposite principle from that illustrated in Figures 1 to 4, theresults obtained are the same. In both cases the same advantages as togradually increasing pressure against the seat under a decreasingtemperature are obtained, in that with the form shown in Figure 5 thefollow spring 14' will .tend to push the valve disk 4' more tightly intoengagement with its seat as the pressure on the rod 8decreases due tocontraction of the bellows until such time as a critical temperature hasbeen reached, when the valve disk was snapped to open position. In bothcases the valve is operated by a valve disk having a uniform movement atthe center and at the periphery and having a uniform tension in oppositedirections or on opposite sides.

The construction disclosed in the present application differs further.from so-called snap valves as'heretofore constructed, in that the snapaction is produced mechanically in both directions under such conditionsthat the opening movement and the closing movement are substantially thesame. With ordinary snap valves in which a lost motion adjustment isutilized, as hereinbefore referred to, there is not such a uniformity ofthe opening and closing movements. This is necessarily true for thereason that with such structures the valve disk starts to closegradually, such gradual movement continuing until the gas-back pressureon the outlet side of the valve isless than the gas pressure on theinlet side. When this condition obtains, the preponderance of pressureon the inlet side completely overcomes the tendency of the valve toremain open, and forces it shut with a quick action so that the snapeifect during closing is obtained by gas pressure as distinguished frommechanical means.

Not only does the lost motion type of valve give non-uniform movementsof the character referred to, but it is necessarily limited toinstallation under such conditions that the gas flow is always in thesame direction. If it were attempted to pass gas, or any other fluidbeing controlled, through the valve in the opposite direction, the valvewould continuously remain away from its seat to the extent permitted bysuch lost motion connection. Such a. valve'is further characterized bythe fact that due to the necessity of extreme accuracy and finallybalancing the parts, the valve is subject to variation caused byvibration.

It is further to be observed that a valve of the character hereindisclosed possesses the additiona1 advantage that since the closingforce is produced mechanically, as distinguished from fluid pressure,the valve is held more tightly closed with the instant structure thanwith constructions of the lost motion type.

Both structures of this application constitute an advanceover the art inthat there is utilized a valve disk having incorporated therewith as apart thereof a flexing member, the action of which, in combination withother parts, serves to instantly throw the valve completely either toits open or to its closed position with a snap action. In addition tothe advantages before set forth, the construction just referred topossesses the advanment in the event of damage by'cracking or losing ofits snap by too high local temperature,

is permitted. Also by-reason of a valve disk which is larger than thediameter of the flexing member, a larger gas capacity is renderedavailable by a smaller movement of the diaphragm.

The adjustable back stop 12 or 12' also possesses the advantage not onlyof making possible an adjustment for various capacities and temperature,but also the advantage that in the event the flexible disk should intime lose some of has tension so as to be unable to snap the valve diskto full capacity, the back stop may be adjusted in such manner that thevalve will snap, but at a smaller capacity. In this manner a snap actionmay be maintained so long as the flexible disk retains a fraction of itsoriginal tension.

Other advantages with respect not only to constructional, but operatingcharacteristics will be apparent to those skilled in the art from theforegoing description taken in connection with the drawing. It will befurther understood that while I have illustrated and described certainpreferred embodiments of my invention, the utility of the invention isnot limited to the structures shown, inasmuch as changes in theconstruction and operation of the parts may be made without departingeither from the spirit of the invention or the scope of my broaderclaims.

I claim:

1. As an article of manufacture, a valve disk having secured thereto asnap action flexing element, said flexing element being carried by andconnected only to the valve disk, and being adapted to be flexed past aplane substantially parallel to the plane of the'valve disk.

2. As an article of manufacture, a valve disk having secured thereto asnap action flexing element, said flexing element being carried by andconnected only to the valve disk, said valve disk being constructed topermit a flexing movement of said element in oppozite directions past aplane substantially parallel to the plane of said disk.

3. As an article of manufacture, a relatively large valve disk and arelatively small imperforate disk centrally carried entirely thereby,and mounted so as to permit flexing of the center of said disk to eitherside of a plane passing through the edges thereof.

4. As an article of manufacture, a relatively large valve disk, and arelatively imperforate small flexible disk centrally carried thereby,said flexible disk being secured to the valve disk at .portion of saidelement havingapproximately equal movement to that of the centralportion and in the opposite direction at the same time.

7. In a valve, a valve disk, a flexible element carried entirely by saiddisk for operating said disk and adapted to impart a snap actionthereto, and means for operating said element to simultaoaaeso neosulyimpart an approximately equal move-- ment to the centralportion in onedirection and to the outer portion thereof in the opposite direction. 1W

8.,In -a-.valve, a valve disk, snap means for operating said diskcarried entirely by said disk and secured thereto at its outer peripheryonly, and an adjustable non-yielding back stop cooperating with saiddisk. 1

9. In a valve, a valve disk, and snap operating means for said disk,said operating means including a flexible element carried entirely bysaid disk and secured at its outer periphery only to said disk, andv anadjustable stop for the valve disk with a yieldable push pin normallyengaging one surface of the snap operating means.

10. In a valve, a valve disk, and snap operating means for said disk,said operating means ineluding an adjustable stop for the valve 'diskwith a yieldable push pin normally engaging one surface of the snapoperating means, and an adjustable back stop cooperating therewith.

11. In a valve, a valve. disk, snap means for operating said diskcarried entirely by said disk and secured thereto at its outer peripheryonly, and means for adjusting the total permissible opening movement ofsaid disk.

, 12. In a valve, a valve member, and a flexible element mounted on andcarried entirely by said member substantially in the plane thereof foroperating the same, said element being normally curved in one directionand adapted to snap to a position of reversed curvature.

13. As an article of manufacture, a valve disk having a rib projectingfrom one side thereof,

and a snap action flexing element having its outer edge portions onlyengaged by said rib.

14. As an article of manufacture, a valve disk having an openingtherethrough, and asnap action flexible'disk overlying said opening andsecured to said disk at its edge portions only.

15. In a valve, a valve member having an opening therethrough, aflexible element of the snap action type overlying said opening andsecured to the valve member, and mechanical means in engagement withopposite sides of said element at all times for producing a mechanicalmovement thereof in each direction, one of said means extending throughsaid opening? 16. As an article of manufacture, a substantially circularvalve disk having a substantially annular rib projecting from one sidethereof, and a substantially circular snap action "flexing elementhaving its outer periphery engaged by said rib.

1'7. As an article of manufacture, a valve disk having secured thereto asnap action flexing disk, said flexing disk being carried'by andconnected only to the valve disk.

18. As an article of manufacture, a valve disk having secured thereto asnap action flexing disk, said flexing disk being carried by andconnected only to the valve disk, said valve disk being constructed topermit a flexing movement of said flexing disk in opposite directions.

19. As an article-of manufacture, a valve disk having secured thereto asnap action flexing disk, said flexing disk being carried by andconnected only to the valve disk, the valve disk and flexing diskforming a unit which is free and unattached to the valve.

ROBERT E. NEWELL.

